[PATCH RFC 4/4] bpf,cgroup,perf: extend bpf-cgroup to support tracepoint attachment
From: Kenny Ho
Date: Thu Nov 18 2021 - 15:29:13 EST
bpf progs are attached to cgroups as usual with the idea of effective
progs remain the same. The perf event / tracepoint's fd is defined as
attachment 'subtype'. The 'subtype' is passed along during attachment
via bpf_attr, reusing replace_bpf_fd field.
After the effective progs are calculated, perf_event is allocated using
the 'subtype'/'fd' value for all cpus filtering on the perf cgroup that
corresponds to the bpf-cgroup (with assumption of a unified hierarchy.)
The effective bpf prog array is then attached to each newly allocated
perf_event and subsequently enabled by activate_effective_progs.
Change-Id: I07a4dcaa0a682bafa496f05411365100d6c84fff
Signed-off-by: Kenny Ho <Kenny.Ho@xxxxxxx>
---
include/linux/bpf-cgroup.h | 15 ++++--
include/linux/perf_event.h | 4 ++
kernel/bpf/cgroup.c | 96 +++++++++++++++++++++++++++++++-------
kernel/cgroup/cgroup.c | 9 ++--
kernel/events/core.c | 45 ++++++++++++++++++
5 files changed, 142 insertions(+), 27 deletions(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index a5e4d9b19470..b6e22fd2aa6e 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -154,6 +154,11 @@ struct cgroup_bpf {
/* cgroup_bpf is released using a work queue */
struct work_struct release_work;
+
+ /* list of perf events (per child cgroups) for tracepoint/kprobe/uprobe bpf attachment to cgroup */
+ /* TODO: array of tp type with array of events for each cgroup
+ * currently only one tp type supported at a time */
+ struct list_head per_cg_events;
};
int cgroup_bpf_inherit(struct cgroup *cgrp);
@@ -161,21 +166,21 @@ void cgroup_bpf_offline(struct cgroup *cgrp);
int __cgroup_bpf_attach(struct cgroup *cgrp,
struct bpf_prog *prog, struct bpf_prog *replace_prog,
- struct bpf_cgroup_link *link,
+ struct bpf_cgroup_link *link, int bpf_attach_subtype,
enum bpf_attach_type type, u32 flags);
int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
struct bpf_cgroup_link *link,
- enum bpf_attach_type type);
+ enum bpf_attach_type type, int bpf_attach_subtype);
int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
union bpf_attr __user *uattr);
/* Wrapper for __cgroup_bpf_*() protected by cgroup_mutex */
int cgroup_bpf_attach(struct cgroup *cgrp,
struct bpf_prog *prog, struct bpf_prog *replace_prog,
- struct bpf_cgroup_link *link, enum bpf_attach_type type,
- u32 flags);
+ struct bpf_cgroup_link *link, int bpf_attach_subtype,
+ enum bpf_attach_type type, u32 flags);
int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
- enum bpf_attach_type type);
+ enum bpf_attach_type type, int bpf_attach_subtype);
int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
union bpf_attr __user *uattr);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 9c440db65c18..5a149d8865a1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -776,6 +776,7 @@ struct perf_event {
#ifdef CONFIG_CGROUP_PERF
struct perf_cgroup *cgrp; /* cgroup event is attach to */
+ struct list_head bpf_cg_list;
#endif
#ifdef CONFIG_SECURITY
@@ -982,6 +983,9 @@ extern void perf_pmu_resched(struct pmu *pmu);
extern int perf_event_refresh(struct perf_event *event, int refresh);
extern void perf_event_update_userpage(struct perf_event *event);
extern int perf_event_release_kernel(struct perf_event *event);
+extern int perf_event_create_for_all_cpus(struct perf_event_attr *attr,
+ struct cgroup *cgroup,
+ struct list_head *entries);
extern struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr,
int cpu,
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 03145d45e3d5..0ecf465ddfb2 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -14,6 +14,8 @@
#include <linux/string.h>
#include <linux/bpf.h>
#include <linux/bpf-cgroup.h>
+#include <linux/perf_event.h>
+#include <linux/trace_events.h>
#include <net/sock.h>
#include <net/bpf_sk_storage.h>
@@ -112,6 +114,8 @@ static void cgroup_bpf_release(struct work_struct *work)
struct bpf_prog_array *old_array;
struct list_head *storages = &cgrp->bpf.storages;
struct bpf_cgroup_storage *storage, *stmp;
+ struct list_head *events = &cgrp->bpf.per_cg_events;
+ struct perf_event *event, *etmp;
unsigned int atype;
@@ -141,6 +145,10 @@ static void cgroup_bpf_release(struct work_struct *work)
bpf_cgroup_storage_free(storage);
}
+ list_for_each_entry_safe(event, etmp, events, bpf_cg_list) {
+ perf_event_release_kernel(event);
+ }
+
mutex_unlock(&cgroup_mutex);
for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
@@ -226,13 +234,16 @@ static bool hierarchy_allows_attach(struct cgroup *cgrp,
*/
static int compute_effective_progs(struct cgroup *cgrp,
enum cgroup_bpf_attach_type atype,
+ int bpf_attach_subtype,
struct bpf_prog_array **array)
{
struct bpf_prog_array_item *item;
struct bpf_prog_array *progs;
struct bpf_prog_list *pl;
struct cgroup *p = cgrp;
- int cnt = 0;
+ struct perf_event *event, *etmp;
+ struct perf_event_attr attr = {};
+ int rc, cnt = 0;
/* count number of effective programs by walking parents */
do {
@@ -245,6 +256,21 @@ static int compute_effective_progs(struct cgroup *cgrp,
if (!progs)
return -ENOMEM;
+ if (atype == CGROUP_TRACEPOINT) {
+ /* TODO: only create event for cgroup that can have process */
+
+ attr.config = bpf_attach_subtype;
+ attr.type = PERF_TYPE_TRACEPOINT;
+ attr.sample_type = PERF_SAMPLE_RAW;
+ attr.sample_period = 1;
+ attr.wakeup_events = 1;
+
+ rc = perf_event_create_for_all_cpus(&attr, cgrp,
+ &cgrp->bpf.per_cg_events);
+ if (rc)
+ goto err;
+ }
+
/* populate the array with effective progs */
cnt = 0;
p = cgrp;
@@ -264,20 +290,41 @@ static int compute_effective_progs(struct cgroup *cgrp,
}
} while ((p = cgroup_parent(p)));
+ if (atype == CGROUP_TRACEPOINT) {
+ list_for_each_entry_safe(event, etmp, &cgrp->bpf.per_cg_events, bpf_cg_list) {
+ rc = perf_event_attach_bpf_prog_array(event, progs);
+ if (rc)
+ goto err_attach;
+ }
+ }
+
*array = progs;
return 0;
+err_attach:
+ list_for_each_entry_safe(event, etmp, &cgrp->bpf.per_cg_events, bpf_cg_list)
+ perf_event_release_kernel(event);
+err:
+ bpf_prog_array_free(progs);
+ return rc;
}
static void activate_effective_progs(struct cgroup *cgrp,
enum cgroup_bpf_attach_type atype,
struct bpf_prog_array *old_array)
{
- old_array = rcu_replace_pointer(cgrp->bpf.effective[atype], old_array,
- lockdep_is_held(&cgroup_mutex));
- /* free prog array after grace period, since __cgroup_bpf_run_*()
- * might be still walking the array
- */
- bpf_prog_array_free(old_array);
+ struct perf_event *event, *etmp;
+
+ if (atype == CGROUP_TRACEPOINT)
+ list_for_each_entry_safe(event, etmp, &cgrp->bpf.per_cg_events, bpf_cg_list)
+ perf_event_enable(event);
+ else {
+ old_array = rcu_replace_pointer(cgrp->bpf.effective[atype], old_array,
+ lockdep_is_held(&cgroup_mutex));
+ /* free prog array after grace period, since __cgroup_bpf_run_*()
+ * might be still walking the array
+ */
+ bpf_prog_array_free(old_array);
+ }
}
/**
@@ -306,9 +353,10 @@ int cgroup_bpf_inherit(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->bpf.progs[i]);
INIT_LIST_HEAD(&cgrp->bpf.storages);
+ INIT_LIST_HEAD(&cgrp->bpf.per_cg_events);
for (i = 0; i < NR; i++)
- if (compute_effective_progs(cgrp, i, &arrays[i]))
+ if (compute_effective_progs(cgrp, i, -1, &arrays[i]))
goto cleanup;
for (i = 0; i < NR; i++)
@@ -328,7 +376,8 @@ int cgroup_bpf_inherit(struct cgroup *cgrp)
}
static int update_effective_progs(struct cgroup *cgrp,
- enum cgroup_bpf_attach_type atype)
+ enum cgroup_bpf_attach_type atype,
+ int bpf_attach_subtype)
{
struct cgroup_subsys_state *css;
int err;
@@ -340,7 +389,8 @@ static int update_effective_progs(struct cgroup *cgrp,
if (percpu_ref_is_zero(&desc->bpf.refcnt))
continue;
- err = compute_effective_progs(desc, atype, &desc->bpf.inactive);
+ err = compute_effective_progs(desc, atype, bpf_attach_subtype,
+ &desc->bpf.inactive);
if (err)
goto cleanup;
}
@@ -424,6 +474,7 @@ static struct bpf_prog_list *find_attach_entry(struct list_head *progs,
* @prog: A program to attach
* @link: A link to attach
* @replace_prog: Previously attached program to replace if BPF_F_REPLACE is set
+ * @bpf_attach_subtype: Type ID of perf tracing event for tracepoint/kprobe/uprobe
* @type: Type of attach operation
* @flags: Option flags
*
@@ -432,7 +483,7 @@ static struct bpf_prog_list *find_attach_entry(struct list_head *progs,
*/
int __cgroup_bpf_attach(struct cgroup *cgrp,
struct bpf_prog *prog, struct bpf_prog *replace_prog,
- struct bpf_cgroup_link *link,
+ struct bpf_cgroup_link *link, int bpf_attach_subtype,
enum bpf_attach_type type, u32 flags)
{
u32 saved_flags = (flags & (BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI));
@@ -454,6 +505,14 @@ int __cgroup_bpf_attach(struct cgroup *cgrp,
if (!!replace_prog != !!(flags & BPF_F_REPLACE))
/* replace_prog implies BPF_F_REPLACE, and vice versa */
return -EINVAL;
+ if ((type == BPF_CGROUP_TRACEPOINT) &&
+ ((flags & BPF_F_REPLACE) || (bpf_attach_subtype < 0) || !(flags & BPF_F_ALLOW_MULTI)))
+ /* replace fd is used to pass the subtype */
+ /* subtype is required for BPF_CGROUP_TRACEPOINT */
+ /* not allow multi BPF progs for the attach type for now */
+ return -EINVAL;
+
+ /* TODO check bpf_attach_subtype is valid */
atype = to_cgroup_bpf_attach_type(type);
if (atype < 0)
@@ -499,7 +558,7 @@ int __cgroup_bpf_attach(struct cgroup *cgrp,
bpf_cgroup_storages_assign(pl->storage, storage);
cgrp->bpf.flags[atype] = saved_flags;
- err = update_effective_progs(cgrp, atype);
+ err = update_effective_progs(cgrp, atype, bpf_attach_subtype);
if (err)
goto cleanup;
@@ -679,7 +738,8 @@ static struct bpf_prog_list *find_detach_entry(struct list_head *progs,
* Must be called with cgroup_mutex held.
*/
int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
- struct bpf_cgroup_link *link, enum bpf_attach_type type)
+ struct bpf_cgroup_link *link, enum bpf_attach_type type,
+ int bpf_attach_subtype)
{
enum cgroup_bpf_attach_type atype;
struct bpf_prog *old_prog;
@@ -708,7 +768,7 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
pl->prog = NULL;
pl->link = NULL;
- err = update_effective_progs(cgrp, atype);
+ err = update_effective_progs(cgrp, atype, bpf_attach_subtype);
if (err)
goto cleanup;
@@ -809,7 +869,7 @@ int cgroup_bpf_prog_attach(const union bpf_attr *attr,
}
}
- ret = cgroup_bpf_attach(cgrp, prog, replace_prog, NULL,
+ ret = cgroup_bpf_attach(cgrp, prog, replace_prog, NULL, attr->replace_bpf_fd,
attr->attach_type, attr->attach_flags);
if (replace_prog)
@@ -832,7 +892,7 @@ int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
if (IS_ERR(prog))
prog = NULL;
- ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type);
+ ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, attr->replace_bpf_fd);
if (prog)
bpf_prog_put(prog);
@@ -861,7 +921,7 @@ static void bpf_cgroup_link_release(struct bpf_link *link)
}
WARN_ON(__cgroup_bpf_detach(cg_link->cgroup, NULL, cg_link,
- cg_link->type));
+ cg_link->type, -1));
cg = cg_link->cgroup;
cg_link->cgroup = NULL;
@@ -961,7 +1021,7 @@ int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
goto out_put_cgroup;
}
- err = cgroup_bpf_attach(cgrp, NULL, NULL, link,
+ err = cgroup_bpf_attach(cgrp, NULL, NULL, link, -1,
link->type, BPF_F_ALLOW_MULTI);
if (err) {
bpf_link_cleanup(&link_primer);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index a645b212b69b..17a1269dc2f9 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6626,25 +6626,26 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd)
#ifdef CONFIG_CGROUP_BPF
int cgroup_bpf_attach(struct cgroup *cgrp,
struct bpf_prog *prog, struct bpf_prog *replace_prog,
- struct bpf_cgroup_link *link,
+ struct bpf_cgroup_link *link, int bpf_attach_subtype,
enum bpf_attach_type type,
u32 flags)
{
int ret;
mutex_lock(&cgroup_mutex);
- ret = __cgroup_bpf_attach(cgrp, prog, replace_prog, link, type, flags);
+ ret = __cgroup_bpf_attach(cgrp, prog, replace_prog, link,
+ bpf_attach_subtype, type, flags);
mutex_unlock(&cgroup_mutex);
return ret;
}
int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
- enum bpf_attach_type type)
+ enum bpf_attach_type type, int bpf_attach_subtype)
{
int ret;
mutex_lock(&cgroup_mutex);
- ret = __cgroup_bpf_detach(cgrp, prog, NULL, type);
+ ret = __cgroup_bpf_detach(cgrp, prog, NULL, type, bpf_attach_subtype);
mutex_unlock(&cgroup_mutex);
return ret;
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d34e00749c9b..71056af4322b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12511,6 +12511,51 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
}
EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
+int perf_event_create_for_all_cpus(struct perf_event_attr *attr,
+ struct cgroup *cgroup,
+ struct list_head *entries)
+{
+ struct perf_event **events;
+ struct perf_cgroup *perf_cgrp;
+ int cpu, i = 0;
+
+ events = kzalloc(sizeof(struct perf_event *) * num_possible_cpus(),
+ GFP_KERNEL);
+
+ if (!events)
+ return -ENOMEM;
+
+ for_each_possible_cpu(cpu) {
+ /* allocate first, connect the cgroup later */
+ events[i] = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, NULL);
+
+ if (IS_ERR(events[i]))
+ goto err;
+
+ i++;
+ }
+
+ perf_cgrp = cgroup_tryget_perf_cgroup(cgroup);
+ if (!perf_cgrp)
+ goto err;
+
+ for (i--; i >= 0; i--) {
+ events[i]->cgrp = perf_cgrp;
+
+ list_add(&events[i]->bpf_cg_list, entries);
+ }
+
+ kfree(events);
+ return 0;
+
+err:
+ for (i--; i >= 0; i--)
+ free_event(events[i]);
+
+ kfree(events);
+ return -ENOMEM;
+}
+
void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
{
struct perf_event_context *src_ctx;
--
2.25.1